dodgeboy67748

i started having problem with the fuel pressure on my truck about a month ago during vacation. it seemed to be dropping off the longer i drove. the fuel tank seemed to be drawing a vacume on it. once i got home i never had any more problems. monday night i drove it about 250 miles round trip. the fuel pressure slowly dropping. by the time i got home it was down to 5 pounds idle and at 75 mph. it use to have 14 pound at idle and 8 at wot.

i have pulled the sending unit and everything looks good. checked the holley blue electric fuel pump on the frame and it is putting out 10-14 pounds. i then checked the pressure at the inlet side of the filter and 10-14 pounds. i checked pressure at the inlet of the injection pump and 10-14 pounds. i replaced the return check valve at the pump and cleaned the filter housing.

i have 10-14 pounds before the motor starts once it starts it drops to 5 or less pounds instantly.

my question is does anybody have any other ideas at where to look. i am needing my pickup asap and have on other ideas. thanks for any suggestions.

vzdude

Try running it without the fuel cap on? Maybe it IS drawing a vaccum on the tank. Only other thing I could think of is a stuck cascade valve in the CP3. I don't think they are replaceable though.

dodgeboy67748

forgot to add that i tried running with the cap off and it didnt help. i checked the codes by cycling the key and i came up with p500-p0177-p1693. i replaced the injection pump about a year ago and replaced the factory lift pump with the holley blue pump.

dodgeboy67748

anybody have any ideas????? i really need my pickup.

John Faughn

This is a general guess , fuel injection system restrict the the return to create pressure , overflow valve in my 12v , pressure regulator in most gassers .
So my guess is something like that in your system , some thing to look for until you get more info .

D2 Cat

Could be your lift pump. Do you have one to change it out to see? Does the pump have an internal spring to determine the pressure? If so maybe you can stretch the spring to get additional pressure.

I've had hydraulic pumps seem to work fine until I need it for a "tad" more weight then I had just used it for, and it wouldn't do it's job. I've had to adjust the pressure relief in those cases.

vzdude

Sorry about the CP3 comment! I assumed it was a 3rd gen! here's some descriptions of the codes. If you are dropping pressure that low when running, one of two things. The VP is letting the fuel past it, or your pressure regulator on the Holley Blue is not set right.

P0177-WATER IN FUEL
P1693-DTC DETECTED IN PCM
P0500-NO VEHICLE SPEED SENSOR SIGNAL

dodgeboy67748

thanks guys. i ordered a new carter pump and it will be here on tuesday and i will try it and see what the out come is. i am hoping that it will fix it. thanks again for the help.

elkchaser

I am having similar problem 2003 HO 6 speed 4x4. Engine surge at above idle speed. accelerates erratic took to dealer could not find problem. any help greatly appreciated